Abstract Social interactions are essential for human health and society. However, the neural circuitry basis for many socialbehaviorsremainsuncertain.Besideclassicalbehaviorssuchasaggression,pairbondingandparenting, recentresearchhasdemonstratedthatrodentsarealsocapableofbehaviorstocomfortdistressedindividuals. Tostudytheneuralbasisoftheseprosocialbehaviors,werecentlyadaptedaprotocolthatproducesconsolation- like behavior in socially monogamous prairie voles to the widely used C57BL/6J mice. Our preliminary experiments indicate an important role for the paraventricular nucleus of the thalamus (PVT) in controlling consolation-likebehaviorinmice.Comfortingadistressedcagemateelicitedrobustc-FosexpressioninthePVT and pharmacogenetic silencing of the PVT dramatically reduced consolation-like behavior. Based on these intriguingresults,weproposeto(Aim1)performinvivocalciumimagingandoptogeneticmanipulationofPVTto determinetheroleofPVTduringconsolation-likebehavior.Incomfortingmice,therewasalsostrongactivation oftheprefrontalcortexandventralsubiculumwhicharemajorinputstothePVT.Wethereforeproposeto(Aim2) identify the inputs responsible for PVT activity during prosocial behavior and expand our understanding of the circuitrywillviraltracing.Theproposedstudiesdefiningtheprosocialneuralcircuitrywilladdtotheknowledge basenecessaryfortreatingconditionswithsocialdeficits.